Abstract
OBJECTIVE: Localized bioimpedance spectroscopy (BIS) is a non-invasive technique for assessing muscle tissue properties. This study examined the test-retest reliability of BIS measurements on the upper trapezius muscle and the effects of body positioning and electrode reapplication. APPROACH: Ten healthy adults (ages 18-30) with no history of neck or shoulder pain participated in the study. BIS measurements were collected over two days across three body positions (prone, seated, seated with neck bent) and with different electrode applications. Key impedance parameters were extracted from Cole-Cole plots. We evaluated measurement reliability, variability, and the minimum detectable change. MAIN RESULTS: BIS measures demonstrated high reliability for primary impedance parameters when body positioning was controlled, whereas model-derived parameters showed greater variability. Impedance parameters differed if the participants were seated or lying prone but were not sensitive to bending the neck to the side. Electrode reapplication did not significantly alter measures unless applied a third time, and sex-related differences were not significant. SIGNIFICANCE: BIS appears to be a reliable method for assessing upper trapezius muscle tissue properties when body position is standardized. Future research should explore BIS applications in larger and more diverse populations and evaluate its potential clinical utility.